One of the new products that we've been working on are laser cut and letterpress business cards. We absolutely love the pillowy look of letterpress, and combining that with laser engraved wood is a truly luxurious effect. One of the challenges we ran into while making them was how to keep the paper side of the cards from getting burned from the laser. Since a laser essentially vaporizes the material you are cutting, you are always going to get some smoke. And as you can guess, heat, smoke, and paper don't really go together well.
Some further investigation online lead me to find some different techniques to mitigate the burn. Here are a few of the things I learned along the way.
1. Fine tuning your settings. Then fine tune again.
Our Epilog came with recommended power and speed settings for our 50 watt laser. It includes materials like wood, acrylic, painted brass, etc. However, there were no recommended settings for paper. Through some experimentation, we dialed the laser in correctly for paper, but what we didn't anticipate was the need to adjust settings throughout the job. Wood will engrave and cut completely differently (even if they are from the same stick of lumber) because different parts of trees (heartwood or sapwood) have different densities, sap content, and resin. There is no simple way to do this other than to be prepared to test a bunch of samples. Also, keeping a close eye on the engraving or laser cutting while the job is running is critical. You might need to increase the speed, power, and frequency of the beam as the variables in the wood change.
2. Get the paper up in the air.
When you cut paper, it's going to create smoke. Smoke will escape from the top and the bottom of the paper, leaving a nasty, sticky, yellow residue on the paper. No matter how much you dial in your laser, you are going to have some residue. One thing you have to do is get it off the laser bed. If the laser hits the bed, it'll leave a burn mark on your paper. We use a jig to both register and get the paper off the ground allowing most of the smoke to be ventilated away from the paper.
3. Mask mask mask.
One surefire way to protect your material is to cover it with a low-tack masking tape. We use this kind. Just be careful not to press it too hard into the paper. Removing it can tear the paper, which is a huge bummer (which we learned after running about 200 business cards). Also, this is going to add a ton of time to your cleanup, so only use it on simple designs (like business cards) or you'll be cursing me for suggesting it. In fact, you might want to even find a different transfer tape, the one we use is good for wood, but a little tough on paper.
4. Focus a hair deep.
When you focus your laser, raise the table a hair so that the focal point is a bit below the paper. We don't know why, but this seems to help with clean edges.
If you have any suggestions or ideas, send us a message!